At first I see it exactly like a P2P, where your territory is the exchange marketplace, and users can pay a small fee for a right to place an offer (which must always be there to decrease spam), and then you get a fee from the exchange (in this case, the zap a reader gives to a post). I think abstracting things down to a P2P exchange actually solves a lot of situations.

The current fee structure is too rigid

How many territories are archived per month?

I haven't taken the time to think through what the right mechanism would be, but you're right that a uniform cost is probably sub-optimal.

I would hazard a guess that some sort of auction would be best: perhaps having an earning goal in mind and selling enough territories to meet it.

The problem there is that I think they want people to be able to create territories instantly and don't want to be organizing and running auctions all the time.